"How is that?" asked Mark. "I don't quite understand."

"Because there is, I believe, a big sheet of ice above us, one, say several hundred feet thick. The same thing is below us, between us and the real bed of the ocean."

"But suppose we have to go up to renew our air supply?" asked Jack.

"We can't go," replied the inventor.

"Then we will die."

"Not necessarily. We will steam along until we come to a place where there is no ice above us."

"But I thought you said there was nothing but ice above us now."

"So there is, but I intend to head due south and there, I believe, we will find an open polar sea. If we do my theory will be proved and we will have made a great discovery."

"Forward then!" exclaimed Jack. "Let us strike for the open sea."

The _Porpoise_ began to move ahead. She steamed slowly, for Mr.

Henderson realized that he was in dangerous waters. He took his position in the conning tower, and had Jack with him to a.s.sist in looking for any obstructions that they might unexpectedly meet.

The big searchlight gave a fine illumination, for the ice above and below reflected back the beams, and what would otherwise have been a sea of darkness was made one of daylight.

The water swarmed with fish, but they were like none that the adventurers had ever seen or dreamed of before. There were monsters with hideous heads, and eyes so large that they occupied nearly half of the ugly bodies.

Then there were serpent-like forms, fish with long slender bodies and whip-fashioned tails, with jaws that extended before them for ten feet or more. Others there were, great lumbering monsters that crawled along on the ice, somewhat as seals do.

After several hours' travel the submarine ran into a school of fish that had shapes like those of polar bears, while their heads were like those of sharks. The creatures swarmed up to the side of the vessel, and some scratched with their claw-like fins on the gla.s.s windows of the conning tower and the side bull's-eyes.

A meal was prepared by Washington, and all the adventurers brought good appet.i.tes to the table. On and on rushed the ship, every hour coming nearer and nearer to the pole.

Professor Henderson had turned the steering of the craft over to Mark, who, with Jack as an a.s.sistant was sending her along at a good speed, when suddenly the submarine seemed to slacken in her progress.

"What's the matter now I wonder?" asked Mark.

"Maybe the engine bearings got hot, and Washington had to slow up to cool them," suggested Jack.

He looked through one of the side windows in the conning tower, a moment later, and uttered a cry of fear.

"What is it?" asked Mark.

Jack pointed with a hand that trembled from fright. Staring at them through the thick gla.s.s of the bull's-eye the boys beheld the most hideous sea monster they had yet encountered.

It seemed to be a vast circular ma.s.s of flesh, twenty feet in diameter, and, in the middle were two openings each three feet across. They were like big holes, and, at the farther end of them could be seen two unblinking eyes. In the centre was a horrible mouth, armed with a triple row of teeth.

Down below there was a short body, at the end of which was a smaller disk, armed with a sharp h.o.r.n.y point.

"What is it?" asked Jack in a whisper.

"I don't know," replied Mark.

A moment later Mr. Henderson came up the companionway into the tower. He caught one glimpse of the monster.

"It is the great sucker of the polar seas!" he exclaimed. "Quick! Speed up the engine! If that one, and the mates of it, fasten on to us we will have trouble!"

He pressed the signal that connected with the engine room, and told Washington to start the engine at its greatest power. The next instant the ship throbbed and trembled under the vibrations of the big screw.

"We may escape!" cried the professor.

As he spoke the ship seemed to come to a sudden stop. The engine could still be felt moving, and the big screw still churned the water to foam in the tunnel, but the craft was stationary.

"We are caught!" exclaimed the professor.

"So we are!"

The windows in the conning tower were darkened. The big sucker had thrown itself forward and spread itself over the gla.s.s, clasping its horrible form half way about the submarine.

"Let's look at the other windows! There may be only one of the creatures!" Mr. Henderson exclaimed, as he hurried down the companion way and into the main cabin. He threw back the slides covering the gla.s.s.

The sight that met his eyes caused him to recoil in horror. There, pressing their shapes against the steel sides, and over the bull's-eyes of the ship were two more of the gigantic suckers!

The ship had now ceased to move, and Washington, in the engine room, feeling that something was wrong, had shut off the power. The adventurers were caught in a trap more terrible than that of the ice, the volcanic mountain, or the Sarga.s.so Sea. It was a trap from which they might never escape.

The suckers, thinking the submarine was perhaps a species of fish, like themselves, and one of their enemies, had fastened on it their fatal vice-like grip. To move through the water, with the weight of all that clinging flesh was impossible.

"What sort of creatures are they?" asked Jack, speaking in a whisper, so great was the terror inspired by the presence of the gigantic sea suckers.

"I never saw any of them before," replied the professor, "but I have read about them. They live only in the polar regions and are a species of octupus, only more terrible. Their powers of suction are enormous, and once they fasten on a fish or animal they never let go until they have absorbed it completely. They act in the same way that a star fish does on an oyster."

"But they can't eat the ship," said Jack.

"No, I fancy the steel and iron sides will prevent them from making a meal of us."

"Then where is the danger?"

"They will not let go until they discover that they cannot devour us, and it may take days. We can only remain under water a comparatively short time at the most. So you see where the danger is."

"But can't we go out and kill them? Then they would let go."

"It would be most risky to venture out, protected even with a diving suit, and carrying the electric guns," the professor went on. "No, I must think of some other plan to free ourselves from the creatures."

"Blow 'em up wif dynamite an' send 'em inter disproportionately contrastedable circ.u.mferences!" exclaimed Washington, who had been listening to the conversation.

"This isn't any time to joke," Mr. Henderson said sternly.

"I wasn't joking," replied the colored man. "Can't we squirt acid on 'em or chop 'em up, or--or--"

"We can do nothing for the time being," said the professor. "Come, we will have a consultation on the subject. Perhaps some one may be able to think of a plan of rescue."